docs: def random_peptides(num, length=9, distribution=None):
      """
      Generate random peptides (kmers).
  
      Parameters
      ----------
      num : int
          Number of peptides to return
  
      length : int
          Length of each peptide
  
      distribution : pandas.Series
          Maps 1-letter amino acid abbreviations to
          probabilities. If not specified a uniform
          distribution is used.
  
      Returns
      ----------
      list of string
  
      """
      if num == 0:
          return []
      if distribution is None:
          distribution = pandas.Series(
              1, index=sorted(amino_acid.COMMON_AMINO_ACIDS))
          distribution /= distribution.sum()
  
      return [
          ''.join(peptide_sequence)
          for peptide_sequence in
          numpy.random.choice(
              distribution.index,
              p=distribution.values,
              size=(int(num), int(length)))
      ]